Fuel-injecting device for internal-combustion engines



Dec. 1,1925. I 1,563,315 I 0. ALT" ET AL FUEL INJECTING DEVICE FORINTERNAL COMBUSTION ENGINES Filed March 27, 1922 Fig.4. Fig.2.

Patented Dec. 1, 1925.

UNITED S ATES PATENT. orrlcli.

OTTO ALT'AND GURT HFLSIG, OF KIEL, GERMANY, ASSIGNORS TO FRIED. KRUPP.AKTIENGESELLSCHAFT GERMANIAWERFT, F KIEL-GAARDEN, GERMANY.

FD'EL-INJ'ECTING DEVICE FOR INTERNAL-COMBUSTION ENGINES.

Application filed March27, 1922. Serial No. 547,323.

To all whom it may concern:

Be it known that we, O'r'ro ALT, residing at Kiel, Germany, and CURTHnLsTo, residing at Kiel, Germany, both citizens of the Republic ofGermany, have invented a certain new and useful Improvement in Fuel-Tnjectin'g Devices for Internal-Combustion Engines, of which thefollowing is a speci- 'fication.

This invention. relates to fuel injecting devices for internalcombustion engines and has more particularly reference to injectingdevices of the kind in which, upon opening a needle valve, the fuel isatomized and carried into the engine cylinder by acurrent of highlycompressed injecting air which flows past the outlet of the fuelchamber.

In the drawings: Fig. 1 is a partial longitudinal section through a fuelinjecting device constructed in accordance with .theinvention;

Fig. 2 is a similar section through a modifiedform of the invention. 1

Referring first to Fig. 1 off the drawings, the device comprises a---.valve cageA in which is mounted a sleeve B which receives the valveneedle 0. The sleeve B is of a shape such asto form" an annular room Fbetween itself and the. valve needle C and 3. annular rooms D and Gbetween itself and the wall of the valve-cage A. The annular rooms D andF are in connection with each other by bores E. The intermediate portionof the sleeve B is enlarged and forms a shoulder separating the room Dfrom the room G. The wall of the valve cage A has a shouldercorresponding to the shoulder of the sleeve B. A packing ring H mountedbetween the said two shoulders provides for an air-tight'joint betweenthesleeve B and the wall of the valve cage A. The lower end of thesleeve B has the shape of a cone b which between itself and the valveneedle C leaves an annular-passage J which is subdivided by narrowlongitudinal ribs pro L by means of the fuel pump (not shown) will -fillthe lower part of the annular room G and will also partially enter intothe annular passage K. The annular rooms D and F contain compressedinjecting air, the pressure of which is higher than the pressure at theend of, the compression in the engine cylinder. The portion of .theannular room G which isnot filled out with fuel, will serve as anair-chamber. When the valve is closed said air-chamber contains a columnof air which has assumed the same pressure as the compressed injectingair, said column of air being completely separated from the compressedinjecting air by the fuel contained in the lower portion of the room G.The volume of the said air-chamber must be such that the degree of exansionvof the air contained therein wil at least be sufficient to pressthe quantity of fuel, which is fed by the fuel pump when the engine isworking at full load. into the jet of injecting air when the needlevalve is opened. a

Upon opening the needle valve 0, the compressed iniecting air flowsthrough the annular passage J into the cylinder. It rushes past theoutletof the annular passage K and produces a vacuum in the same. At thesame time the column of air contained in the annular room G expands anddrives the fuel through the annular passage K into the jet of compressedinjecting air.

If the annular room G is of suitable dimensions, the entering of thefuel into the cylinder will not take place suddenly because of the rapiddecrease of the ressure of the column of air contained in t e room (Jrabove the fuel, but the fuel will enter the cylinder with a certainretardation. Besides, as already mentioned, the quantity of. aircontained'in the air-chamber needs only be so large that, when theengine is working at full load, the maximum quantity of fuel fed by thepump will justbe pressed into the jet of injecting air, so thatafterwards the air in the air-chamber will be entirely expanded.

Fuel injecting devices are now in use in which the air of injection isdivided into 1 two branches within the nozzle, the fuel being drivenforward by the air in one branch 7 and atomized in the other branch. Incom-.

parison with these well-known fuel injecting tial advantage that,especially when the engine is Working at low loads and thereforenecessitates only small quantities of fuel, no subsequent flowing-in ofair of importance will take place after the period of fuel-injectionhassbeen finished. ,Moreover, since the room G will always containsubstantially the same air which is alternately compressed and expandedin the same manner as the air of the well-known air-chambers, theportion of said air which might still flow after the fuel will be hi hlyheated which will be of afavorable influence on the process ofcombustion.

The modification illustrated by Fig. 2 deviates from the constructionhereinbefore described inasmuch as means are provided for changing thevolume of the room G. These means comprise an adjustable internallythreaded -collar N which may be screwed up and down on the sleeve Bwhich is provided with external threads on the ortion situated intheroom G. An air tight joint is formed between thecollar N and the wallof the valve cage A by means of a packing ring a which is mounted in anannular dove-tailed groove of the collar N. The cone 6 is removablyfastened to the sleeve B for the purpose of allowing the collar N to bemounted on the sleeve B. This type of atomizer is preferably used fordetermining the volume of the annular room G in engines of a new type orit may be successfully applied to engines designed to be driven by heavyas well as by light fuels.

Claims: 1

1. In a fuel injector for internal combustion engines, a fuel chamber, afuel inlet and an injecting air inlet communicating with said chamber,and means whereby air is trapped in said chamber by the fuel charge andcompressed in dependence upon the pressure of the injecting air, thecharge being expelled from said chamber under the expansive force ofsaid air upon the operation of the injector.

2. Fuel injector for internal combustion engines comprising a valve forcontrolling a cylinder inlet, a fuel chamber, and an air pressurechamber, said chambers being 1n v connection only by respective outletchannels confluent at the cylinder inlet, said fuel chamber beingentirely closed above the level of the fuel therein whereby an aircushion is formed above said fuel level.

3. In combination with an internal combustion engine cylinder, a valvecage, a valve needle mounted therein, a port in said cylinder controlledby said needle, a fuel chamber, achamber containing air under pressure,a passage communicating between said fuel chamber, said air chamber andsaid cylinder port, said fuel chamber being entirely closed above thelevel of the fuel therein whereby said cylinder port being closed an aircushion is formed in said fuel chamber, said air cushion tending toexpel the fuel from said fuel chamber with a force balanced by thecontrary force existing in said air chamber, and-means whereby saidcylinder port being opened fuel is expelled from said fuel chamber bythe expanding action of said air cushion and delivered to saidcombustion cyllnder under the combined influence of said expandingaction and said air under pressure.

4. A fuel injecting device for internalcombustion engines, comprising incombination a valve cage, a needle valve, a fuel room and a room forcompressed injecting air, an air-chamber formed in connection with saidfuel room, said air-chamber being entire] closed and situated in theinterior -of t e device, and means for varying the' volume of saidair-chamber, the air contained in said air-chamber being adapted toexpand and to press the fuel into the jet of compressed injecting airwhen the needle valve is opened, and to assume again the pressure of theinjecting air when the needle .valve has been closed.

ing air tight above the level of the fuel therein whereby an air chamberis formed above said fuel level, the air contained in said air-chamberbeing adapted to expand and to press the fuel into the jet of compressedinjecting air when the needle valve is opened,

and to assume again the pressure of the injecting air when the needlevalve has been closed.

6. A fuel injecting device for internal combustion engines, comprising avalve cage and a valve needle mounted therein, a cylindrical sleeve alsomounted in said valve cage and concentrically surrounding the valveneedle, two annular rooms being formed between the cylindrical sleeve,the valve cage and the valve needle, one room containing fuel and theother room-containing compressed injecting air, both rooms havingcoinciding outlets, and air contained in the first-mentioned room abovethe fuel, this room being larger than is necessary for the reception ofthe fuel and air tight above the level of the fuel therein so that, uponopening the needle valve,'the expansion of the air above the fuel willat least suffice to press the quantity of fuel which is fed into saidroom when the engine is working at full load, into the jet of compressedair leaving the room containing the same.

7. A fuel injecting device for internal combustion engines, comprising avalve cage and a valve needle mounted therein, a cylindrical sleeve alsomounted in said valve ca e and concentrically surrounding the va veneedle, 21 room for receiving fuel and aroom for receiving compressedinjecting air being formed by the cylindrical sleeve, the valve cage andthe valve needle, the fuel room forming at the sametime an air-chamber,and the said cyhndrlcal sleeve having an externally screw-threadedportion situv ated in the said air-chamber, an internally threadedcollar adjustably mounted on said threaded portion of the cylindricalsleeve,

and means on said collar for providing an air-tight joint between thecollar and the wall of the valve cage.

- .OTTO' ALT.

CURT HELSIG.

